On Aug 17, 2001 12:55 -0500, Mark H. Wood wrote:> Regarding the need to do more than just zero unwanted data, I note that> there is a U.S. DOD MIL-SPEC (no, I do not know the number) which defines> a sequence of patterns to be used for erasing magnetic media.

In the Usenix paper quoted earlier in this thread (I believe) it wasstated that the MIL-SPEC document was actually bogus. REAL securedeletion requirements were much more strict (something like 15 passes ofvarious random and non-random patterns vs. 7 passes of alternating all 0and all 1 data), but the US government made it think that the MIL-SPECrequirements were enough, so that naive users would follow it, stillleaving enough trace data on the disk for the government to retrieve it.

Still, even a single pass of zero writes is enough to prevent 99.9%of attackers from getting the data back.